French fries, the juicy fat on the outer edge of that delicious pork chop, and chocolate donuts are not among the “good fat” choices, but many other sources of fat, such as fish, should be a part of your meal plans.

We know fat is necessary for brain function, but why?

Johns Hopkins researchers, reporting in the October 29, 2010 Neuron, found a surprising connection between palmitate, a fatty acid occurring naturally in the brain, and memories and learning.

Palmitate “marks” brain proteins, called N-methyl-D-aspartate receptors (NMDA), that must be activated for long-term memory and learning to happen.

This substance “directs the receptors to specific locations in the outer membrane of brain cells, which strengthen and weaken their connections with each other, sculpting and resculpting new memory circuits,” says Richard L. Huganir, Ph.D., professor and director of the Solomon H. Snyder Department of Neuroscience at Johns Hopkins School of Medicine.

Surprisingly, Huganir and his team found this to be a reversible process with possibilities for enhancing or even erasing memory. If we assume that there is some sort of switch that turns on and off, the process could conceivably be manipulated to aid in learning and preserving memory in persons with dementia.

“Before now, no one knew that NMDA receptors change in response to the addition of palmitate,” adds Huganir.

It has been known that glutamate, a brain signaling chemical, activates NMDA receptors, which allows neurons to communicate. Scientists did not know, however, what allowed this receptor to work, or what “caused it to make its way to the synapse, the specialized part of a nerve cell where communication takes place.”

In the research scientists first fed radioactive palmitate to live neurons in a dish, and then separated out the NMDA receptors. They subsequently tracked the radioactivity on X-ray film and discovered that the palmitate had attached to the NMDA receptors.

Next, the scientists put both the altered receptors and normal ones into cells outside the brain that don’t normally manufacture NMDA receptors, and were subsequently able to see where on the receptor the palmitate attached.

Results showed that the NMDA receptor undergoes “dual palmitoylation, in 2 different regions.” The fat attaching to the first area stabilizes the receptors on the surface of neurons, while in the second region the receptors accumulate inside the neurons.

What is becoming clear to scientists is that palmitate regulates both NMDA receptors and other brain proteins during the signaling process. So if this palmitoylation process does not take place, learning and memory impairment may result, i.e., no NMDA receptors at the synapses, no communication between neurons.

So what is the relationship between diet and the level of palmitate?

Huganir states that the palmitate level in the brain is affected by diet, but is present at high levels already. “Palmitate is made even if you don’t eat much fat.”

Most people are not deficient in palmitate unless they are chronically malnourished, but the difference between good and bad fats is important for optimal health. Brain food should come from quality sources like fish rather than artery cloggers like McBreakfast muffins.

The more highly processed a food is, the more likely it is to be high in saturated fats and refined sugars.

A slice or 2 of bacon or crumb cake now and then is okay, but a steady diet of these foods, plus seemingly “healthy” foods that come in boxed, processed form such as mashed potato mixes, rice mixes, pasta mixes and gingersnap cookies are not the least bit beneficial to health.

It can’t be said enough: seafood is an excellent source of the omega 3 fatty acids that are so high in palmitate.